topology: Create package_cpus sysfs attribute

The existing sysfs cpu/topology/core_siblings (and core_siblings_list)
attributes are documented, implemented, and used by programs to represent
set of logical CPUs sharing the same package.

This makes sense if the next topology level above a core is always a
package.  But on systems where there is a die topology level between a core
and a package, the name and its definition become inconsistent.

So without changing its function, add a name for this map that describes
what it actually is -- package CPUs -- the set of CPUs that share the same
package.

This new name will be immune to changes in topology, since it describes
threads at the current level, not siblings at a contained level.

Suggested-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d9d3228b82fb5665e6f93a0ccd033fe022558521.1557769318.git.len.brown@intel.com

diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index 2ff8a1e..48af5c2 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -46,15 +46,15 @@
 	human-readable list of cpuX's hardware threads within the same
 	core as cpuX.
 
-core_siblings:
+package_cpus:
 
-	internal kernel map of cpuX's hardware threads within the same
-	physical_package_id.
+	internal kernel map of the CPUs sharing the same physical_package_id.
+	(deprecated name: "core_siblings")
 
-core_siblings_list:
+package_cpus_list:
 
-	human-readable list of cpuX's hardware threads within the same
-	physical_package_id.
+	human-readable list of CPUs sharing the same physical_package_id.
+	(deprecated name: "core_siblings_list")
 
 book_siblings: